rebaseline_server: add ImagePair class, a step towards new intermediate JSON schema

gm/rebaseline_server/imagepair.py

+#!/usr/bin/python
+
+"""
+Copyright 2014 Google Inc.
+
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+
+ImagePair class (see class docstring for details)
+"""
+
+import posixpath
+
+class ImagePair(object):
+  """
+  Describes a pair of images, along with optional metadata (pixel difference
+  metrics, whether to ignore mismatches, etc.)
+  """
+
+  def __init__(self, image_diff_db,
+               base_url, imageA_relative_url, imageB_relative_url,
+               expectations=None, extra_columns=None):
+    """
+    Args:
+      image_diff_db: ImageDiffDB instance we use to generate/store image diffs
+      base_url: base of all image URLs
+      imageA_relative_url: URL pointing at an image, relative to base_url
+      imageB_relative_url: URL pointing at an image, relative to base_url
+      expectations: optional dictionary containing expectations-specific
+          metadata (ignore-failure, bug numbers, etc.)
+      extra_columns: optional dictionary containing more metadata (test name,
+          builder name, etc.)
+    """
+    self.base_url = base_url
+    self.imageA_relative_url = imageA_relative_url
+    self.imageB_relative_url = imageB_relative_url
+    self.expectations_dict = expectations
+    self.extra_columns_dict = extra_columns
+    if imageA_relative_url == imageB_relative_url:
+      self.diff_record = None
+    else:
+      # TODO(epoger): Rather than blocking until image_diff_db can read in
+      # the image pair and generate diffs, it would be better to do it
+      # asynchronously: tell image_diff_db to download a bunch of file pairs,
+      # and only block later if we're still waiting for diff_records to come
+      # back.
+      image_diff_db.add_image_pair(
+          expected_image_locator=imageA_relative_url,
+          expected_image_url=posixpath.join(base_url, imageA_relative_url),
+          actual_image_locator=imageB_relative_url,
+          actual_image_url=posixpath.join(base_url, imageB_relative_url))
+      self.diff_record = image_diff_db.get_diff_record(
+          expected_image_locator=imageA_relative_url,
+          actual_image_locator=imageB_relative_url)
+
+  def as_dict(self):
+    """
+    Return a dictionary describing this ImagePair, as needed when constructing
+    the JSON representation.
+    """
+    asdict = {
+        'imageAUrl': self.imageA_relative_url,
+        'imageBUrl': self.imageB_relative_url,
+    }
+    if self.expectations_dict:
+      asdict['expectationsData'] = self.expectations_dict

[rmistry, 2014/02/10 17:34:54]

Keep the names of the keys as top-level constants?

[epoger, 2014/02/10 18:01:16]

Done.

+    if self.extra_columns_dict:
+      asdict['extraColumnValues'] = self.extra_columns_dict
+    if self.diff_record and (self.diff_record.get_num_pixels_differing() > 0):
+      asdict['isDifferent'] = True
+      asdict['differenceData'] = self.diff_record.as_dict()
+    else:
+      asdict['isDifferent'] = False
+    return asdict